Conventionally, a heat exchanger for exchanging heat between fluid such as a refrigerant and air has been known and widely used in air conditioners and similar apparatuses. As such heat exchanger, as disclosed in Patent document 1, for example, a heat exchanger in which a multiplicity of flat sheet-like fins are arranged along a heat transfer tube at predetermined pitches is known. In this type of heat exchanger, fluid such as refrigerant flows through the heat transfer tube, while air passes between the fins disposed at the predetermined pitches, thereby exchanging heat between the fluid and air.
Patent document 1: Unexamined Patent Publication No. 2001-304783